Synthesis and characterization of TiO2/ZnO core/shell nanomaterials for solar cell applications

TiO2/ZnO core/shell nanomaterials were synthesized in two steps involving preparation of core TiO2 nanoparticles by simple hydrolysis and growth of ZnO shell layers on core TiO2 nanoparticles by refluxing methods. Structural characterization by XRD confirmed the formation of anatase TiO2 and high crystalline wurtzite structured ZnO on the surface of TiO2, agreeing with Raman measurements. Here, a significant increase in the intensity of photoluminescence peak for ZnO-coated TiO2 than bare TiO2 infers the recombination of the photogenerated charge carriers. The current–voltage measurements of solar cell based on Eosin yellowish dye-sensitized TiO2 and TiO2/ZnO films showed an enhancement of open circuit voltage (Voc) from 0.278 to 0.412 V, when ZnO is added. This confirms its active role for the energy barrier leading to decrease in recombination losses.

► TiO2/ZnO offers energy barrier at the nanoparticle/electrolyte interface.
► Especially, individual core nanoparticles exhibit energy barrier.
► Emission intensity variation implies recombination of the charge carriers.
► Addition of ZnO enhances open circuit voltage in DSSC.